Fuel injector having a nozzle with improved cooling

Abstract

A fuel injector having a nozzle with improved cooling including a retainer and a nozzle housing received therein. The nozzle housing includes a nozzle shank, an outer peripheral surface and at least one injection hole at a tip of the nozzle shank. The nozzle shank is positioned in a nozzle support portion of the retainer. In one embodiment, the outer peripheral surface of the nozzle shank is tapered, and the inner peripheral surface of the nozzle support portion is correspondingly tapered and sized to engage the outer peripheral surface of the nozzle shank along a tapered interface. In another embodiment, the inner peripheral surface of the nozzle support portion has a diameter smaller than a diameter of the outer peripheral surface of the nozzle shank so that an interference fit exists at a seal interface. In yet another embodiment, a nozzle seal seals an interface between the inner peripheral surface of the retainer and the outer peripheral surface of the nozzle shank to thereby prevent entry of hot gases into the interface. In another embodiment, the nozzle support portion is provided on a nozzle sleeve.

1. A closed nozzle fuel injector with improved cooling, said fuel injector being sized to be received in an injector bore of a cylinder head of an internal combustion engine, said fuel injector comprising:
 a substantially tubular retainer having a proximal end with a nozzle support portion, said nozzle support portion having an outer peripheral surface and an engagement opening with an inner peripheral surface; and 
 a nozzle housing received within said retainer at said proximal end, said nozzle housing including an integral nozzle shank with an outer peripheral surface and a longitudinal axis, said integral nozzle shank having an elongated shape in which a longitudinal axial dimension of said integral nozzle shank along said longitudinal axis is larger than a diameter of said outer peripheral surface of said integral nozzle shank, said integral nozzle shank further having an elongated valve cavity adapted to receive a valve element therein, and a plurality of injection holes at a tip of the nozzle shank which are adapted to spray fuel when said valve element is moved within said elongated valve cavity, said valve element contacting said integral nozzle shank to prevent flow to said at least one injection hole when said valve element is closed in said elongated valve cavity; 
 wherein said integral nozzle shank and said nozzle support portion define an annular portion of said engagement opening between said integral nozzle shank and said nozzle support portion, and said inner peripheral surface of said nozzle support portion has a diameter adjacent to said tip that is smaller than said diameter of said outer peripheral surface of said integral nozzle shank adjacent to said tip in a manner that an interference fit exists at a seal interface between said integral nozzle shank and said nozzle support portion, said seal interface being positioned adjacent to said tip of the nozzle shank when said integral nozzle shank is installed in said nozzle support portion to prevent combustion gas from passing through said seal interface and entering said annular portion of said engagement opening between said integral nozzle shank and said nozzle support portion, said retainer engaging an outer barrel, and having a longitudinal axial dimension along said longitudinal axis of said nozzle housing that is larger than said longitudinal axial dimension of said integral nozzle shank. 
 
   
   
     2. The fuel injector of  claim 1 , wherein the diameter of the inner peripheral surface of said nozzle support portion is sized approximately 0.00005 to 0.001 inch smaller than the diameter of said outer peripheral surface of said nozzle shank. 
   
   
     3. The fuel injector of  claim 2 , wherein the diameter of the inner peripheral surface of said nozzle support portion is sized approximately 0.0001 to 0.0006 smaller than the diameter of said outer peripheral surface of said nozzle shank. 
   
   
     4. The fuel injector of  claim 1 , wherein said nozzle support portion includes a chamfer adapted to facilitate installation of said nozzle shank into said nozzle support portion. 
   
   
     5. The fuel injector of  claim 4 , wherein the diameter of the inner peripheral surface of said nozzle support portion is sized approximately 0.00005 to 0.001 inch smaller than the diameter of said outer peripheral surface of said nozzle shank. 
   
   
     6. The fuel injector of  claim 5 , wherein the diameter of the inner peripheral surface of said nozzle support portion is sized approximately 0.0001 to 0.0006 inch smaller than the diameter of said outer peripheral surface of said nozzle shank. 
   
   
     7. The fuel injector of  claim 1 , wherein the nozzle shank is press fitted into said engagement opening of said nozzle support portion. 
   
   
     8. The fuel injector of  claim 1 , wherein said retainer further includes a nozzle sleeve and said nozzle support portion is provided on said nozzle sleeve. 
   
   
     9. A closed nozzle fuel injector with improved cooling for an internal combustion engine comprising:
 a substantially tubular retainer means having a proximal end with a nozzle support portion, said nozzle support portion having an outer peripheral surface and an engagement opening with an inner peripheral surface; and 
 a nozzle housing received within said retainer means at said proximal end, said nozzle housing including an integral nozzle shank with an outer peripheral surface and a longitudinal axis, said integral nozzle shank having an elongated shape in which a longitudinal axial dimension of said integral nozzle shank along said longitudinal axis is larger than a diameter of said outer peripheral surface of said integral nozzle shank, said integral nozzle shank further having an elongated valve cavity adapted to receive a valve element therein, and a plurality of injection holes at a tip of the nozzle shank which are adapted to spray fuel when said valve element is moved within said elongated valve cavity, said valve element contacting said integral nozzle shank to prevent flow to said at least one injection hole when said valve element is closed in said elongated valve cavity; 
 wherein said integral nozzle shank and said nozzle support portion define an annular portion of said engagement opening between said integral nozzle shank and said nozzle support portion, and said inner peripheral surface of said nozzle support portion has a diameter adjacent to said tip that is smaller than said diameter of said outer peripheral surface of said integral nozzle shank adjacent to said tip in a manner that an interference fit exists at a seal interface between said integral nozzle shank and said nozzle support portion, said seal interface being positioned adjacent to said tip of the nozzle shank when said integral nozzle shank is installed in said nozzle support portion to prevent combustion gas from entering said annular portion of said engagement opening between said integral nozzle shank and said nozzle support portion, said retainer means engaging an outer barrel, and having a longitudinal axial dimension along said longitudinal axis of said nozzle housing that is larger than said longitudinal axial dimension of said integral nozzle shank. 
 
   
   
     10. A closed nozzle fuel injector with improved cooling for an internal combustion engine comprising:
 a substantially tubular retainer having a proximal end with a nozzle support portion, said nozzle support portion having an outer peripheral surface and an engagement opening with an inner peripheral surface; 
 a nozzle housing received within said retainer at said proximal end, said nozzle housing including an integral nozzle shank with an outer peripheral surface and a longitudinal axis, said integral nozzle shank having an elongated shape in which a longitudinal axial dimension of said integral nozzle shank along said longitudinal axis is larger than a diameter of said outer peripheral surface of said integral nozzle shank, said integral nozzle shank further having an elongated valve cavity adapted to receive a valve element therein, and a plurality of injection holes at a tip of the nozzle shank which are adapted to spray fuel when said valve element is moved within said elongated valve cavity, said valve element contacting said integral nozzle shank to prevent flow to said at least one injection hole when said valve element is closed in said elongated valve cavity; and 
 a barrel that engages said substantially tubular retainer; 
 wherein said integral nozzle shank and said nozzle support portion define an annular portion of said engagement opening between said integral nozzle shank and said nozzle support portion, and said inner peripheral surface of said nozzle support portion has a diameter adjacent said tip that is smaller than said diameter of said outer peripheral surface of said integral nozzle shank adjacent to said tip in a manner that an interference fit exists at a seal interface adjacent to said tip of the nozzle shank between said integral nozzle shank and said nozzle support portion when said integral nozzle shank is installed in said nozzle support portion to prevent combustion gas from entering said annular portion of said engagement opening between said integral nozzle shank and said nozzle support portion through said seal interface, said retainer having a longitudinal axial dimension along said longitudinal axis of said nozzle housing that is larger than said longitudinal axial dimension of said integral nozzle shank. 
 
   
   
     11. A closed nozzle fuel injector with improved cooling, said fuel injector comprising:
 a substantially tubular retainer having a proximal end with a nozzle support portion, said nozzle support portion having an outer peripheral surface and an engagement opening with an inner peripheral surface; and 
 a nozzle housing received within said retainer at said proximal end, said nozzle housing including an integral nozzle shank with an outer peripheral surface and an elongated valve cavity adapted to receive a valve element therein, and a plurality of injection holes at a tip of the nozzle shank which are adapted to spray fuel when said valve element is moved within said elongated valve cavity, said valve element contacting said integral nozzle shank to prevent flow to said at least one injection hole when said valve element is closed in said elongated valve cavity; 
 wherein said integral nozzle shank and said nozzle support portion define an annular portion of said engagement opening, and said inner peripheral surface of said nozzle support portion has a diameter adjacent to said tip that is smaller than said diameter of said outer peripheral surface of said integral nozzle shank adjacent to said tip in a manner that an interference fit exists at a seal interface between said integral nozzle shank and said nozzle support portion that is positioned adjacent to said tip of the nozzle shank to prevent combustion gas from passing through said seal interface and entering said annular portion of said engagement opening, said retainer engaging an outer barrel, and having a longitudinal axial dimension along said longitudinal axis of said nozzle housing that is larger than said longitudinal axial dimension of said integral nozzle shank.